OBJECTIVETo develop a simple and rapid capillary electrophoresis (CE) method for the separation and determination of four active organic acids including salicylic acid, syringic acid, benzoic acid, and anthranilic acid in Radix Isatidis.

METHODThe HPCE system consisted of a fused-silica capillary column of 47.3 cm (38.3 cm to the detector) x50 microm i.d. and a mixture ofacetonitrile-borate buffer (15% acetonitrile, 25 mmol L(-1) borate, 15 mmol L(-1) beta-CD, pH 9.10) solution as the operating buffer. The applied voltage was 11.5 kV and the UV detection was set at 220 nm. The effects of the applied voltage, detection wavelength, and the pH of buffer, the concentration of buffer, acetonitrile and beta-CD were investigated.

RESULTThe linear calibration rang was 3.0-90 mg L(-1) (r=0.9994) for salylic acid, 4.0-120 mg L(-1) (r=0.9995) for syringic acid, 2.0-60 mg L(-1) (r=0.9998) for benzoic acid and 5.0-100 mg L(-1) (r=0.9992) for anthranilic acid. The recoveries of salylic acid, syringic acid, benzoic acid and anthranilic acid were 95.9%-102.6%, 98.6%-103.4%, 98.7%-104.1%, 96.1%-104.3% respectively. The detection limits of salylic acid, syringic acid, benzoic acid and anthranilic acid were 0.7, 1.1, 1.2 and 1.5 mg L(-1), respectively.